Photon speeds up the loading of images and photos on your site, which means less load on your web server and faster images for your readers.
Photon is a service that Jetpack offers to help speed up image loading on your site. You can enable it easily in: Jetpack Settings > Appearance.
That’s it! There’s nothing more you need to do. You’ll still upload and add your images just like you normally would, but Jetpack Photon will intercept those images before they are loaded to the page and make sure they are sized as best as possible for loading quickly on your site.